linux/drivers/input/ff-memless.c
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   1/*
   2 *  Force feedback support for memoryless devices
   3 *
   4 *  Copyright (c) 2006 Anssi Hannula <anssi.hannula@gmail.com>
   5 *  Copyright (c) 2006 Dmitry Torokhov <dtor@mail.ru>
   6 */
   7
   8/*
   9 * This program is free software; you can redistribute it and/or modify
  10 * it under the terms of the GNU General Public License as published by
  11 * the Free Software Foundation; either version 2 of the License, or
  12 * (at your option) any later version.
  13 *
  14 * This program is distributed in the hope that it will be useful,
  15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 * GNU General Public License for more details.
  18 *
  19 * You should have received a copy of the GNU General Public License
  20 * along with this program; if not, write to the Free Software
  21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  22 */
  23
  24/* #define DEBUG */
  25
  26#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  27
  28#include <linux/slab.h>
  29#include <linux/input.h>
  30#include <linux/module.h>
  31#include <linux/mutex.h>
  32#include <linux/spinlock.h>
  33#include <linux/jiffies.h>
  34#include <linux/fixp-arith.h>
  35
  36MODULE_LICENSE("GPL");
  37MODULE_AUTHOR("Anssi Hannula <anssi.hannula@gmail.com>");
  38MODULE_DESCRIPTION("Force feedback support for memoryless devices");
  39
  40/* Number of effects handled with memoryless devices */
  41#define FF_MEMLESS_EFFECTS      16
  42
  43/* Envelope update interval in ms */
  44#define FF_ENVELOPE_INTERVAL    50
  45
  46#define FF_EFFECT_STARTED       0
  47#define FF_EFFECT_PLAYING       1
  48#define FF_EFFECT_ABORTING      2
  49
  50struct ml_effect_state {
  51        struct ff_effect *effect;
  52        unsigned long flags;    /* effect state (STARTED, PLAYING, etc) */
  53        int count;              /* loop count of the effect */
  54        unsigned long play_at;  /* start time */
  55        unsigned long stop_at;  /* stop time */
  56        unsigned long adj_at;   /* last time the effect was sent */
  57};
  58
  59struct ml_device {
  60        void *private;
  61        struct ml_effect_state states[FF_MEMLESS_EFFECTS];
  62        int gain;
  63        struct timer_list timer;
  64        struct input_dev *dev;
  65
  66        int (*play_effect)(struct input_dev *dev, void *data,
  67                           struct ff_effect *effect);
  68};
  69
  70static const struct ff_envelope *get_envelope(const struct ff_effect *effect)
  71{
  72        static const struct ff_envelope empty_envelope;
  73
  74        switch (effect->type) {
  75        case FF_PERIODIC:
  76                return &effect->u.periodic.envelope;
  77
  78        case FF_CONSTANT:
  79                return &effect->u.constant.envelope;
  80
  81        default:
  82                return &empty_envelope;
  83        }
  84}
  85
  86/*
  87 * Check for the next time envelope requires an update on memoryless devices
  88 */
  89static unsigned long calculate_next_time(struct ml_effect_state *state)
  90{
  91        const struct ff_envelope *envelope = get_envelope(state->effect);
  92        unsigned long attack_stop, fade_start, next_fade;
  93
  94        if (envelope->attack_length) {
  95                attack_stop = state->play_at +
  96                        msecs_to_jiffies(envelope->attack_length);
  97                if (time_before(state->adj_at, attack_stop))
  98                        return state->adj_at +
  99                                        msecs_to_jiffies(FF_ENVELOPE_INTERVAL);
 100        }
 101
 102        if (state->effect->replay.length) {
 103                if (envelope->fade_length) {
 104                        /* check when fading should start */
 105                        fade_start = state->stop_at -
 106                                        msecs_to_jiffies(envelope->fade_length);
 107
 108                        if (time_before(state->adj_at, fade_start))
 109                                return fade_start;
 110
 111                        /* already fading, advance to next checkpoint */
 112                        next_fade = state->adj_at +
 113                                        msecs_to_jiffies(FF_ENVELOPE_INTERVAL);
 114                        if (time_before(next_fade, state->stop_at))
 115                                return next_fade;
 116                }
 117
 118                return state->stop_at;
 119        }
 120
 121        return state->play_at;
 122}
 123
 124static void ml_schedule_timer(struct ml_device *ml)
 125{
 126        struct ml_effect_state *state;
 127        unsigned long now = jiffies;
 128        unsigned long earliest = 0;
 129        unsigned long next_at;
 130        int events = 0;
 131        int i;
 132
 133        pr_debug("calculating next timer\n");
 134
 135        for (i = 0; i < FF_MEMLESS_EFFECTS; i++) {
 136
 137                state = &ml->states[i];
 138
 139                if (!test_bit(FF_EFFECT_STARTED, &state->flags))
 140                        continue;
 141
 142                if (test_bit(FF_EFFECT_PLAYING, &state->flags))
 143                        next_at = calculate_next_time(state);
 144                else
 145                        next_at = state->play_at;
 146
 147                if (time_before_eq(now, next_at) &&
 148                    (++events == 1 || time_before(next_at, earliest)))
 149                        earliest = next_at;
 150        }
 151
 152        if (!events) {
 153                pr_debug("no actions\n");
 154                del_timer(&ml->timer);
 155        } else {
 156                pr_debug("timer set\n");
 157                mod_timer(&ml->timer, earliest);
 158        }
 159}
 160
 161/*
 162 * Apply an envelope to a value
 163 */
 164static int apply_envelope(struct ml_effect_state *state, int value,
 165                          struct ff_envelope *envelope)
 166{
 167        struct ff_effect *effect = state->effect;
 168        unsigned long now = jiffies;
 169        int time_from_level;
 170        int time_of_envelope;
 171        int envelope_level;
 172        int difference;
 173
 174        if (envelope->attack_length &&
 175            time_before(now,
 176                        state->play_at + msecs_to_jiffies(envelope->attack_length))) {
 177                pr_debug("value = 0x%x, attack_level = 0x%x\n",
 178                         value, envelope->attack_level);
 179                time_from_level = jiffies_to_msecs(now - state->play_at);
 180                time_of_envelope = envelope->attack_length;
 181                envelope_level = min_t(u16, envelope->attack_level, 0x7fff);
 182
 183        } else if (envelope->fade_length && effect->replay.length &&
 184                   time_after(now,
 185                              state->stop_at - msecs_to_jiffies(envelope->fade_length)) &&
 186                   time_before(now, state->stop_at)) {
 187                time_from_level = jiffies_to_msecs(state->stop_at - now);
 188                time_of_envelope = envelope->fade_length;
 189                envelope_level = min_t(u16, envelope->fade_level, 0x7fff);
 190        } else
 191                return value;
 192
 193        difference = abs(value) - envelope_level;
 194
 195        pr_debug("difference = %d\n", difference);
 196        pr_debug("time_from_level = 0x%x\n", time_from_level);
 197        pr_debug("time_of_envelope = 0x%x\n", time_of_envelope);
 198
 199        difference = difference * time_from_level / time_of_envelope;
 200
 201        pr_debug("difference = %d\n", difference);
 202
 203        return value < 0 ?
 204                -(difference + envelope_level) : (difference + envelope_level);
 205}
 206
 207/*
 208 * Return the type the effect has to be converted into (memless devices)
 209 */
 210static int get_compatible_type(struct ff_device *ff, int effect_type)
 211{
 212
 213        if (test_bit(effect_type, ff->ffbit))
 214                return effect_type;
 215
 216        if (effect_type == FF_PERIODIC && test_bit(FF_RUMBLE, ff->ffbit))
 217                return FF_RUMBLE;
 218
 219        pr_err("invalid type in get_compatible_type()\n");
 220
 221        return 0;
 222}
 223
 224/*
 225 * Only left/right direction should be used (under/over 0x8000) for
 226 * forward/reverse motor direction (to keep calculation fast & simple).
 227 */
 228static u16 ml_calculate_direction(u16 direction, u16 force,
 229                                  u16 new_direction, u16 new_force)
 230{
 231        if (!force)
 232                return new_direction;
 233        if (!new_force)
 234                return direction;
 235        return (((u32)(direction >> 1) * force +
 236                 (new_direction >> 1) * new_force) /
 237                (force + new_force)) << 1;
 238}
 239
 240#define FRAC_N 8
 241static inline s16 fixp_new16(s16 a)
 242{
 243        return ((s32)a) >> (16 - FRAC_N);
 244}
 245
 246static inline s16 fixp_mult(s16 a, s16 b)
 247{
 248        a = ((s32)a * 0x100) / 0x7fff;
 249        return ((s32)(a * b)) >> FRAC_N;
 250}
 251
 252/*
 253 * Combine two effects and apply gain.
 254 */
 255static void ml_combine_effects(struct ff_effect *effect,
 256                               struct ml_effect_state *state,
 257                               int gain)
 258{
 259        struct ff_effect *new = state->effect;
 260        unsigned int strong, weak, i;
 261        int x, y;
 262        s16 level;
 263
 264        switch (new->type) {
 265        case FF_CONSTANT:
 266                i = new->direction * 360 / 0xffff;
 267                level = fixp_new16(apply_envelope(state,
 268                                        new->u.constant.level,
 269                                        &new->u.constant.envelope));
 270                x = fixp_mult(fixp_sin16(i), level) * gain / 0xffff;
 271                y = fixp_mult(-fixp_cos16(i), level) * gain / 0xffff;
 272                /*
 273                 * here we abuse ff_ramp to hold x and y of constant force
 274                 * If in future any driver wants something else than x and y
 275                 * in s8, this should be changed to something more generic
 276                 */
 277                effect->u.ramp.start_level =
 278                        clamp_val(effect->u.ramp.start_level + x, -0x80, 0x7f);
 279                effect->u.ramp.end_level =
 280                        clamp_val(effect->u.ramp.end_level + y, -0x80, 0x7f);
 281                break;
 282
 283        case FF_RUMBLE:
 284                strong = (u32)new->u.rumble.strong_magnitude * gain / 0xffff;
 285                weak = (u32)new->u.rumble.weak_magnitude * gain / 0xffff;
 286
 287                if (effect->u.rumble.strong_magnitude + strong)
 288                        effect->direction = ml_calculate_direction(
 289                                effect->direction,
 290                                effect->u.rumble.strong_magnitude,
 291                                new->direction, strong);
 292                else if (effect->u.rumble.weak_magnitude + weak)
 293                        effect->direction = ml_calculate_direction(
 294                                effect->direction,
 295                                effect->u.rumble.weak_magnitude,
 296                                new->direction, weak);
 297                else
 298                        effect->direction = 0;
 299                effect->u.rumble.strong_magnitude =
 300                        min(strong + effect->u.rumble.strong_magnitude,
 301                            0xffffU);
 302                effect->u.rumble.weak_magnitude =
 303                        min(weak + effect->u.rumble.weak_magnitude, 0xffffU);
 304                break;
 305
 306        case FF_PERIODIC:
 307                i = apply_envelope(state, abs(new->u.periodic.magnitude),
 308                                   &new->u.periodic.envelope);
 309
 310                /* here we also scale it 0x7fff => 0xffff */
 311                i = i * gain / 0x7fff;
 312
 313                if (effect->u.rumble.strong_magnitude + i)
 314                        effect->direction = ml_calculate_direction(
 315                                effect->direction,
 316                                effect->u.rumble.strong_magnitude,
 317                                new->direction, i);
 318                else
 319                        effect->direction = 0;
 320                effect->u.rumble.strong_magnitude =
 321                        min(i + effect->u.rumble.strong_magnitude, 0xffffU);
 322                effect->u.rumble.weak_magnitude =
 323                        min(i + effect->u.rumble.weak_magnitude, 0xffffU);
 324                break;
 325
 326        default:
 327                pr_err("invalid type in ml_combine_effects()\n");
 328                break;
 329        }
 330
 331}
 332
 333
 334/*
 335 * Because memoryless devices have only one effect per effect type active
 336 * at one time we have to combine multiple effects into one
 337 */
 338static int ml_get_combo_effect(struct ml_device *ml,
 339                               unsigned long *effect_handled,
 340                               struct ff_effect *combo_effect)
 341{
 342        struct ff_effect *effect;
 343        struct ml_effect_state *state;
 344        int effect_type;
 345        int i;
 346
 347        memset(combo_effect, 0, sizeof(struct ff_effect));
 348
 349        for (i = 0; i < FF_MEMLESS_EFFECTS; i++) {
 350                if (__test_and_set_bit(i, effect_handled))
 351                        continue;
 352
 353                state = &ml->states[i];
 354                effect = state->effect;
 355
 356                if (!test_bit(FF_EFFECT_STARTED, &state->flags))
 357                        continue;
 358
 359                if (time_before(jiffies, state->play_at))
 360                        continue;
 361
 362                /*
 363                 * here we have started effects that are either
 364                 * currently playing (and may need be aborted)
 365                 * or need to start playing.
 366                 */
 367                effect_type = get_compatible_type(ml->dev->ff, effect->type);
 368                if (combo_effect->type != effect_type) {
 369                        if (combo_effect->type != 0) {
 370                                __clear_bit(i, effect_handled);
 371                                continue;
 372                        }
 373                        combo_effect->type = effect_type;
 374                }
 375
 376                if (__test_and_clear_bit(FF_EFFECT_ABORTING, &state->flags)) {
 377                        __clear_bit(FF_EFFECT_PLAYING, &state->flags);
 378                        __clear_bit(FF_EFFECT_STARTED, &state->flags);
 379                } else if (effect->replay.length &&
 380                           time_after_eq(jiffies, state->stop_at)) {
 381
 382                        __clear_bit(FF_EFFECT_PLAYING, &state->flags);
 383
 384                        if (--state->count <= 0) {
 385                                __clear_bit(FF_EFFECT_STARTED, &state->flags);
 386                        } else {
 387                                state->play_at = jiffies +
 388                                        msecs_to_jiffies(effect->replay.delay);
 389                                state->stop_at = state->play_at +
 390                                        msecs_to_jiffies(effect->replay.length);
 391                        }
 392                } else {
 393                        __set_bit(FF_EFFECT_PLAYING, &state->flags);
 394                        state->adj_at = jiffies;
 395                        ml_combine_effects(combo_effect, state, ml->gain);
 396                }
 397        }
 398
 399        return combo_effect->type != 0;
 400}
 401
 402static void ml_play_effects(struct ml_device *ml)
 403{
 404        struct ff_effect effect;
 405        DECLARE_BITMAP(handled_bm, FF_MEMLESS_EFFECTS);
 406
 407        memset(handled_bm, 0, sizeof(handled_bm));
 408
 409        while (ml_get_combo_effect(ml, handled_bm, &effect))
 410                ml->play_effect(ml->dev, ml->private, &effect);
 411
 412        ml_schedule_timer(ml);
 413}
 414
 415static void ml_effect_timer(unsigned long timer_data)
 416{
 417        struct input_dev *dev = (struct input_dev *)timer_data;
 418        struct ml_device *ml = dev->ff->private;
 419        unsigned long flags;
 420
 421        pr_debug("timer: updating effects\n");
 422
 423        spin_lock_irqsave(&dev->event_lock, flags);
 424        ml_play_effects(ml);
 425        spin_unlock_irqrestore(&dev->event_lock, flags);
 426}
 427
 428/*
 429 * Sets requested gain for FF effects. Called with dev->event_lock held.
 430 */
 431static void ml_ff_set_gain(struct input_dev *dev, u16 gain)
 432{
 433        struct ml_device *ml = dev->ff->private;
 434        int i;
 435
 436        ml->gain = gain;
 437
 438        for (i = 0; i < FF_MEMLESS_EFFECTS; i++)
 439                __clear_bit(FF_EFFECT_PLAYING, &ml->states[i].flags);
 440
 441        ml_play_effects(ml);
 442}
 443
 444/*
 445 * Start/stop specified FF effect. Called with dev->event_lock held.
 446 */
 447static int ml_ff_playback(struct input_dev *dev, int effect_id, int value)
 448{
 449        struct ml_device *ml = dev->ff->private;
 450        struct ml_effect_state *state = &ml->states[effect_id];
 451
 452        if (value > 0) {
 453                pr_debug("initiated play\n");
 454
 455                __set_bit(FF_EFFECT_STARTED, &state->flags);
 456                state->count = value;
 457                state->play_at = jiffies +
 458                                 msecs_to_jiffies(state->effect->replay.delay);
 459                state->stop_at = state->play_at +
 460                                 msecs_to_jiffies(state->effect->replay.length);
 461                state->adj_at = state->play_at;
 462
 463        } else {
 464                pr_debug("initiated stop\n");
 465
 466                if (test_bit(FF_EFFECT_PLAYING, &state->flags))
 467                        __set_bit(FF_EFFECT_ABORTING, &state->flags);
 468                else
 469                        __clear_bit(FF_EFFECT_STARTED, &state->flags);
 470        }
 471
 472        ml_play_effects(ml);
 473
 474        return 0;
 475}
 476
 477static int ml_ff_upload(struct input_dev *dev,
 478                        struct ff_effect *effect, struct ff_effect *old)
 479{
 480        struct ml_device *ml = dev->ff->private;
 481        struct ml_effect_state *state = &ml->states[effect->id];
 482
 483        spin_lock_irq(&dev->event_lock);
 484
 485        if (test_bit(FF_EFFECT_STARTED, &state->flags)) {
 486                __clear_bit(FF_EFFECT_PLAYING, &state->flags);
 487                state->play_at = jiffies +
 488                                 msecs_to_jiffies(state->effect->replay.delay);
 489                state->stop_at = state->play_at +
 490                                 msecs_to_jiffies(state->effect->replay.length);
 491                state->adj_at = state->play_at;
 492                ml_schedule_timer(ml);
 493        }
 494
 495        spin_unlock_irq(&dev->event_lock);
 496
 497        return 0;
 498}
 499
 500static void ml_ff_destroy(struct ff_device *ff)
 501{
 502        struct ml_device *ml = ff->private;
 503
 504        kfree(ml->private);
 505}
 506
 507/**
 508 * input_ff_create_memless() - create memoryless force-feedback device
 509 * @dev: input device supporting force-feedback
 510 * @data: driver-specific data to be passed into @play_effect
 511 * @play_effect: driver-specific method for playing FF effect
 512 */
 513int input_ff_create_memless(struct input_dev *dev, void *data,
 514                int (*play_effect)(struct input_dev *, void *, struct ff_effect *))
 515{
 516        struct ml_device *ml;
 517        struct ff_device *ff;
 518        int error;
 519        int i;
 520
 521        ml = kzalloc(sizeof(struct ml_device), GFP_KERNEL);
 522        if (!ml)
 523                return -ENOMEM;
 524
 525        ml->dev = dev;
 526        ml->private = data;
 527        ml->play_effect = play_effect;
 528        ml->gain = 0xffff;
 529        setup_timer(&ml->timer, ml_effect_timer, (unsigned long)dev);
 530
 531        set_bit(FF_GAIN, dev->ffbit);
 532
 533        error = input_ff_create(dev, FF_MEMLESS_EFFECTS);
 534        if (error) {
 535                kfree(ml);
 536                return error;
 537        }
 538
 539        ff = dev->ff;
 540        ff->private = ml;
 541        ff->upload = ml_ff_upload;
 542        ff->playback = ml_ff_playback;
 543        ff->set_gain = ml_ff_set_gain;
 544        ff->destroy = ml_ff_destroy;
 545
 546        /* we can emulate periodic effects with RUMBLE */
 547        if (test_bit(FF_RUMBLE, ff->ffbit)) {
 548                set_bit(FF_PERIODIC, dev->ffbit);
 549                set_bit(FF_SINE, dev->ffbit);
 550                set_bit(FF_TRIANGLE, dev->ffbit);
 551                set_bit(FF_SQUARE, dev->ffbit);
 552        }
 553
 554        for (i = 0; i < FF_MEMLESS_EFFECTS; i++)
 555                ml->states[i].effect = &ff->effects[i];
 556
 557        return 0;
 558}
 559EXPORT_SYMBOL_GPL(input_ff_create_memless);
 560